An example of endomycorrhiza is
Mycorrhiza is a mutually beneficial or symbiotic association of a fungus with the root of a higher plant. The fungal partner absorbs nutrients for the plant and the plant provides food and shelter to the fungus. Depending upon the residence of the fungus, mycorrhiza can be of 2 types- endomycorrhiza (fungal hyphae reside inside the roots) and ectomycorrhiza (fungal hyphae reside on the surface of the roots).
The genus Glomus forms endomycorrhiza, a symbiotic association with plants. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant. Plants having such associations show other benefits also, such as resistance to root borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development. Hence option b is the correct answer.
Anabaena is a symbiotic nitrogen fixing cyanobacteria.
Frankia is a symbiotic nitrogen fixing bacteria.
Agaricus is a species of mushroom which is not found in mycorrhizal associations.